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Improvement of Phosphorus and Heavy Metals Retention in Stormwater Treatment

Zhang, Wei
The objectives of this study were to find filter media with high phosphorus sorption and adequate hydraulic conductivity for use in bioretention cells, and to evaluate the improvement of heavy metals retention in sandy soil after amending with fly ash. Batch sorption experiments were used to screen filter media. Column experiment and transport modeling allowed the evaluation of phosphorus and heavy metals sorption in a dynamic condition. Soils had a low phosphorus sorption while fly ash had the highest. The addition of fly ash in soils increased phosphorus sorption, but decreased the hydraulic conductivity. Sandy soil amended with fly ash exhibited a high phosphorus sorption while maintaining adequate hydraulic conductivity. Sandy soil had the lowest heavy metals sorption while fly ash the highest. Adding fly ash in sandy soil increased the heavy metals sorption. Fly ash-amended sand could improve the phosphorus and heavy metals retention in stormwater infiltration systems.